An Ethernet switch commonly has a fixed forwarding latency for packet transmission. However, under congestion, queuing delays add to the forwarding latency and add variability that has been hard to measure, or predict, at any given time.
There have been many advancements in managing congestion in a network using quality of service and various congestion notifications. Examples of the state of the art in this field are the teachings of U.S. Pat. No. 6,560,648, US 2010/0293243, and US 2011/0019558.
These common techniques, however, do not provide any information about the latency of the network. In addition, network latency, as measured by round trip from point A to point B provides the average latency over a time window but does not provide any further detail on where the delays occurred and exactly at what time.
Another limitation with known techniques is that they only provide the lowest or best-case latency, which is insufficient in newer low latency applications. Forwarding latency of switches used to be tens of microseconds but is decreasing with newer technology. Achieving low latency has become essential in high-speed systems used for high frequency trading and other high performance computing applications. High latency caused by network congestion has a major negative impact on these types of applications. The known tools, however, are not able to provide the needed information in these newer circumstances.
In view of the above, there is a need for improved techniques for networking test and measurement.